1. Field of the Invention
The present invention relates to ventilating equipment for railway rolling stock and an operating method thereof and, more particularly, to ventilating equipment for railway rolling stock suitable for use on a high-speed train in which there takes place a change in atmospheric pressure outside of cars of the train which makes passengers feel uncomfortable.
2. Description of the Prior Art
When the rolling stock train) is running at a high speed in a tunnel, the external pressure of the train (a pressure outside of the cars) in the tunnel changes. Particularly a value of external pressure fluctuation of the train reaches a maximum when trains pass each other in the tunnel. For example, when the train is running in a tunnel at a running speed of 200 km/h and the ratio of sectional area of the car to the tunnel is 0.23, the external pressure fluctuation value is about 150 mmH.sub.2 O on the positive pressure side and about 400 mmH.sub.2 O on the negative pressure side. Generally, the external pressure fluctuation value increases in proportion to a square of the running speed of the train. If such a pressure change propagates into the cars of the train, ear discomfort is experienced by the passengers. To overcome this problem of propagation of the pressure change into the cars, conventional cars are built airtight and equipped with a ventilating equipment. The ventilating equipment has a ventilating air volume necessary for holding the concentration of O.sub.2 C in the cars, i.e. a required ventilating air volume. There is an example of this ventilating equipment disclosed in Japanese Utility Model Registration No. 1287276 (counterpart of U.S. Pat. No. 3,563,155). The ventilating equipment that has been put into practical use, air blowers comprising a supply air means and an exhaust air means have a capacity of delivering the maximum pressure of 540 mmH.sub.2 O and the air volume of 30 m.sup.3 /min. The car provided with this ventilating equipment has the inside capacity of a car body of about 150 m.sup.3 and the seating capacity of 100 passengers on both sides. In this ventilating equipment the discharge pressure of the blower is set higher than the variation value of the external pressure. To operate the train at a higher speed, it is necessary to increase the discharge pressure of the air blowers. However, for improving the discharge pressure of the air blowers, it is imperative to build large-sized air blowers and, accordingly, to increase a power consumption for driving these blowers.
Alternative ventilating equipment is proposed in Laid-Open Japanese Patent Application No. 62-227852, wherein air flow paths are designed to be closed or contracted when trains pass each other in a tunnel. However, when it is presumed that the train is running at a speed of 400 km/h, a fluctuation value of the maximum pressure during travel in the tunnel is supposed to reach 1600 mmH.sub.2 O. Even under the condition that the train is traveling in a tunnel without passing by any oncoming train, the value of pressure change may reach 600 mmH.sub.2 O. It is, therefore, necessary to close the air flow paths of the ventilating equipment while the train is running in the tunnel. Besides, in this ventilating equipment, the ventilating air volume is prone to decrease with the improvement of car speeds.
Furthermore, another prior-art ventilating equipment disclosed in Laid Open Japanese Patent Application No. 62-203868 is provided with turbocompressors as air supply and exhaust means. The turbocompressor is capable of obtaining a great discharge pressure over a fluctuation value of an external pressure of cars during high-speed running. The turbocompressor, however, decreases in efficiency when operated to supply the amount of air equivalent to a required ventilating air volume at a low discharge pressure The turbocharger stated above, therefore, requires much more power than a blower in use in ordinary ventilating equipment. In the meantime, the rolling stock has the problem that the feed efficiency decreases with the improvement of the running speed. In the high-speed running train, therefore, it is undesirable to increase the power consumption in the ventilating equipment.
It is an object of the present invention to provide a ventilating equipment for rolling stock capable of continuously ventilating the cars without increasing the power consumption when the car running speed increases, and a method of operating the same.